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autonomous asked

48V LiFePo4 Battery with MPPT Maximum Output Voltage exceeding 61v

I have a 2180W PV array in series providing 189V (13A Max) to a Victron 250/60 feeding a 48v battery bank with LiFePo4 200A BMS batteries. I am using the battery setting "Smart Lithium (LiFePo4)" to manage output to the battery bank. 56.8V is supposed to be the max output voltage however it frequently exceeds 61V and this is causing issues with my inverter which flips into max input voltage protection mode. This controller should never exceed 57-58V but it does frequently going from Absorb to Float and my invert shuts down. I am new to Victron but I have 12 or so off grid systems operational for many years using other controllers which don't have issues using presets. They work right out of the box as they should. Since this is my first experience with Victron and these controllers cost considerably more I was expecting an easy plug n play setup.

I have checked all cables fuses and wiring. I have turned off the controller removing all power and turned it back on. I have update all firmware and apps. I have turned off the PV array and back on again. When PV is off the inverter works fine for as long as I have power in the batteries.

Is there a way to limit the MPPT output to keep it from spiking the batteries/inverter with 60V or more because the "Smart Lithium (LiFePo4)" preset is not working to spec and a 48V battery bank should not be subjected to 60V+?

Any other suggestions are welcome.

48volt charging
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autonomous avatar image
autonomous answered ·

So let me get this straight Victron wants you to buy an MPPT purpose built to charge battery banks and calls it SMART but in reality it can't read advanced batteries at all and requires yet another piece of hardware (GX) to communicate with them even though the manual says you don't technically need it. In addition making a DEFAULT setting that is wildly overvolted is dangerous and wrong but the controller has no way to know when it is happening so yeah a built-in fire hazard regardless of the settings. Victron's parts all come from China anyway so how come all of China's controllers are capable but somehow this expensive Victron brand cant figure it out without an upsell? Also after reading the manual and the settings the default mode has voltage presets that do not exceed the spec but then DO ANYWAY so yeah their is that. Sorry been there done that!

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Justin Cook avatar image Justin Cook ♦♦ commented ·
"Smart" means it has bluetooth, not that it can magically query your battery chemistry.


Not sure why you think Victron's parts come from China, as that's largely not the case either... and also not at all the case that any Chinese controller in existence will magically query your battery chemistry.


I suspect that a bit of due diligence would have perhaps tempered the odd and unrealistic set of expectations demonstrated here, but eh so it goes... good luck with your magic Chinese controllers, I guess?

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dragotog avatar image
dragotog answered ·

not sure about you config but you need a gx device or a smart bluetooth mppt or ve.direct bluetooth smart dongle


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autonomous avatar image autonomous commented ·
I have a Smartsolar 250/60 tr that is about 4 feet from the batteries. Although I appreciate your input if a modern mppt controller can't tell what the battery charge state is then it has already failed as a product. In this case I have a decent smart controller.
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nickdb avatar image
nickdb answered ·

That profile is specific to a Victron battery. you would usually create a user defined profile and make sure the values are set correctly for your needs.

Does the system have a GX? Does your BMS communicate with it?

Can you show charts of the behaviour?

Voltage spikes can occur if a BMS disconnects and PV has nowhere else to go.

If the Voltage is sustained then it is worth checking that the readings at the charger and battery are the same and you don't have any loss in the connection.

Double check temperature compensation isn't on.



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autonomous avatar image autonomous commented ·

I have 4x TimeUSB 200ah (Li Time 200A BMS) not Victron batteries. If Victron forces customers to utilize their batteries only they are making a HUGE mistake but I doubt that is the case.

This system does not need a GX which is overkill and just upselling fancy gadgetry that ultimately will tell you the same thing as the logs in a Smart controller. I don't have the temp comp enabled. There is no connection loss this was tested using two multi meters and once by bypassing the ANL fuse.

I was finally able to figure out what was happening using the BT Interface logs and hopefully I have corrected the issue. It seems that the Victron controller will send > 59.67V to the battery bank on default "Smart Lithium (LiFePo4)" Absorb mode, however the setting indicates 56.8V Max Absorb which is misleading. Small voltage fluctuations will cause the controller to overload the BMS on my batteries so they shut off temporarily and my inverter cycles.

The Victron controller default Absorb mode setting for LiFePO4 is suspect to say the least or maybe I just have a bad controller. Manually setting the Max Absorb mode down to 56V cured the spiking issue for the last few days. In addition the system has run through each cycle daily Bulk, Absorb, Float with a max output of 57.6V under the new setting (Still over the setting specified of 56V by 1.6V !!!).

In any case considering the many different controllers I have worked with I can say with confidence this is not a plug n play "SMART CONTROLLER" and requires tweaks taking the "SMART" right out of it. In addition I would also maintain spikes as high as I have seen should never occur under any circumstances right out of the box using default LiFePO4 settings from the manufacturer. I purpose Victron make specific battery presets for the Victron brand of LiFePO4, if this is the issue, instead of wrecking customer expectations every time they use off-brand batteries ( a scenario that's true 90% of the time). Anyway it seems to be working now so I'll let it run a week or so and update this post with the results.

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kevgermany avatar image kevgermany ♦♦ autonomous commented ·
The controllers come with a manual which explains the settings. The batteries should come with a manual which tells you what settings are needed.

As you have no GX device, there is no way for the battery BMS to communicate it's requirements to the MPPT. In this situation the installer must ensure the settings are correct. Failure to do so will invalidate the Victron warranty and probably the battery warranty.

There's a warning in the manual that expert knowledge/advice is needed in setting up the system. From your comments it's clear you didn't do this.


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